In the past, the carton designers of molded cartons have produced cartons with beak type locks. However, such prior designs and constructions have relatively weak engaging surfaces and are subject to rupture and failure when opening is attempted. In some instances the beak formed on the base or tray section fails and in other instances the orifice formed in the front wall of the cover section ruptures. The problem of failure and rupture was ever present in prior constructions. Although, over the years, many good designers attempted to produce improved locks, failures and ruptures still occurred and the problem was not completely solved.
Examples of prior designs appear in the U.S. Pat. Nos. to Alsman, 3,217,963; Friday, 3,245,600; Hartman, 3,276,656; Bagay, 3,459,360; and Seest et al, 3,471,078. In esch of these prior designs, developed over the years, and with practical experience, the orifice engagement surface remained simple. Seest et al. attempted to reinforce their beak with a horizontal rib at the very top thereof away from the latch engaging surface. It was not obvious to any of the prior workers in the field to provide a horizontal peripheral rib at the engaging surface or a vertical surface extending upwardly therefrom.
Many of these prior carton locks may also be relatively easily disengaged by movement of the cover section forward relative to the base section of the carton. Bagay U.S. Pat. No. 3,459,360, however, discloses the interengagement of the back of the beak with the top of the opening.